1. Field of the Invention
The present invention relates to an image forming apparatus and method.
2. Description of the Related Art
There is an image forming apparatus having an electronic sort function used when printing a plurality of copies of a document.
In the electronic sort function for a print engine, page data on print images is generated for all of a plurality of document pages included in a specified job, and the page data on those print images is temporarily stored in a mass storage device such as a hard disk drive (HDD) or a random access memory (RAM) disk drive, and loaded into a video memory according to a printing order to thereby execute printing thereof. For example, in a case where two copies of a two-page document are printed, the page data on the two pages is first generated and stored in the mass storage device. (a) Then, the page data corresponding to the first page of the first copy is loaded into the video memory and printed, and after completion of the printing, the corresponding page data is deleted from the video memory. (b) Then, the page data corresponding to the second page of the first copy is loaded into the video memory and printed, and after completion of the printing, the corresponding page data is deleted from the video memory. (c) Then, the page data corresponding to the first page of the second copy is loaded into the video memory and printed, and after completion of the printing, the corresponding page data is deleted from the video memory. (d) Then, the page data corresponding to the second page of the second copy is loaded into the video memory and printed, and after completion of the printing, the corresponding page data is deleted from the video memory.
However, according to the above-mentioned art, each time one page is printed, the page data is loaded into the video memory from a low-speed mass storage device that takes much time in reading data. Accordingly, it takes a long time to process a printing request when using an electronic sort function.